[PATCH linux next v3] net: stmmac: remove software VLAN tag stripping

[PATCH linux next v3] net: stmmac: remove software VLAN tag stripping

[he.peilin]

The software VLAN stripping logic in stmmac_rx_vlan() was originally
introduced in 2014 by commit b93819854d6e ("stmmac: Add vlan rx for
better GRO performance.") as a workaround to improve GRO performance,
since at that time GRO could not handle frames with VLAN tags. However,
this limitation was resolved in 2015 by commit 66e5133f19e9 ("vlan: Add
GRO support for non hardware accelerated vlan"), which added GRO support
for non-hardware-accelerated VLAN frames. Keeping a software fallback
path for VLAN stripping is no longer necessary and only adds complexity.

Fixes: b93819854d6e ("stmmac: Add vlan rx for better GRO performance.")
Signed-off-by: Peilin He <he.peilin@zte.com.cn>
Reviewed-by: xu xin <xu.xin16@zte.com.cn>
Reviewed-by: Jiang Kun <jiang.kun2@zte.com.cn>
---
 .../net/ethernet/stmicro/stmmac/stmmac_main.c | 28 ++-----------------
 1 file changed, 2 insertions(+), 26 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index b2b7d0242dd3..2e3b0cf10d66 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -5021,24 +5021,6 @@ static netdev_features_t stmmac_features_check(struct sk_buff *skb,
 	return vlan_features_check(skb, features);
 }

-static void stmmac_rx_vlan(struct net_device *dev, struct sk_buff *skb)
-{
-	struct vlan_ethhdr *veth = skb_vlan_eth_hdr(skb);
-	__be16 vlan_proto = veth->h_vlan_proto;
-	u16 vlanid;
-
-	if ((vlan_proto == htons(ETH_P_8021Q) &&
-	     dev->features & NETIF_F_HW_VLAN_CTAG_RX) ||
-	    (vlan_proto == htons(ETH_P_8021AD) &&
-	     dev->features & NETIF_F_HW_VLAN_STAG_RX)) {
-		/* pop the vlan tag */
-		vlanid = ntohs(veth->h_vlan_TCI);
-		memmove(skb->data + VLAN_HLEN, veth, ETH_ALEN * 2);
-		skb_pull(skb, VLAN_HLEN);
-		__vlan_hwaccel_put_tag(skb, vlan_proto, vlanid);
-	}
-}
-
 /**
  * stmmac_rx_refill - refill used skb preallocated buffers
  * @priv: driver private structure
@@ -5407,9 +5389,7 @@ static void stmmac_dispatch_skb_zc(struct stmmac_priv *priv, u32 queue,
 	if (priv->hw->hw_vlan_en)
 		/* MAC level stripping. */
 		stmmac_rx_hw_vlan(priv, priv->hw, p, skb);
-	else
-		/* Driver level stripping. */
-		stmmac_rx_vlan(priv->dev, skb);
+
 	skb->protocol = eth_type_trans(skb, priv->dev);

 	if (unlikely(!coe) || !stmmac_has_ip_ethertype(skb))
@@ -5901,9 +5881,6 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
 		if (priv->hw->hw_vlan_en)
 			/* MAC level stripping. */
 			stmmac_rx_hw_vlan(priv, priv->hw, p, skb);
-		else
-			/* Driver level stripping. */
-			stmmac_rx_vlan(priv->dev, skb);

 		skb->protocol = eth_type_trans(skb, priv->dev);

@@ -7964,9 +7941,8 @@ static int __stmmac_dvr_probe(struct device *device,
 	ndev->features |= ndev->hw_features | NETIF_F_HIGHDMA;
 	ndev->watchdog_timeo = msecs_to_jiffies(watchdog);
 #ifdef STMMAC_VLAN_TAG_USED
-	/* Both mac100 and gmac support receive VLAN tag detection */
-	ndev->features |= NETIF_F_HW_VLAN_CTAG_RX | NETIF_F_HW_VLAN_STAG_RX;
 	if (dwmac_is_xmac(priv->plat->core_type)) {
+		ndev->features |= NETIF_F_HW_VLAN_CTAG_RX;
 		ndev->hw_features |= NETIF_F_HW_VLAN_CTAG_RX;
 		priv->hw->hw_vlan_en = true;
 	}
-- 
2.27.0

Re: [PATCH linux next v3] net: stmmac: remove software VLAN tag stripping

[Maxime Chevallier]

Hi,

On 9/1/26 11:28, he.peilin@zte.com.cn wrote:
> The software VLAN stripping logic in stmmac_rx_vlan() was originally
> introduced in 2014 by commit b93819854d6e ("stmmac: Add vlan rx for
> better GRO performance.") as a workaround to improve GRO performance,
> since at that time GRO could not handle frames with VLAN tags. However,
> this limitation was resolved in 2015 by commit 66e5133f19e9 ("vlan: Add
> GRO support for non hardware accelerated vlan"), which added GRO support
> for non-hardware-accelerated VLAN frames. Keeping a software fallback
> path for VLAN stripping is no longer necessary and only adds complexity.

Thanks for the followup, but please slow down, you must wait 24h between
submissions :

https://docs.kernel.org/process/maintainer-netdev.html

While at it, please take a look at the rules about the topic name, must be
either 'net' or 'net-next'

I'll review after the 24h cooldown,

Thanks,

Maxime

> 
> Fixes: b93819854d6e ("stmmac: Add vlan rx for better GRO performance.")
> Signed-off-by: Peilin He <he.peilin@zte.com.cn>
> Reviewed-by: xu xin <xu.xin16@zte.com.cn>
> Reviewed-by: Jiang Kun <jiang.kun2@zte.com.cn>
> ---
>  .../net/ethernet/stmicro/stmmac/stmmac_main.c | 28 ++-----------------
>  1 file changed, 2 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index b2b7d0242dd3..2e3b0cf10d66 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -5021,24 +5021,6 @@ static netdev_features_t stmmac_features_check(struct sk_buff *skb,
>  	return vlan_features_check(skb, features);
>  }
> 
> -static void stmmac_rx_vlan(struct net_device *dev, struct sk_buff *skb)
> -{
> -	struct vlan_ethhdr *veth = skb_vlan_eth_hdr(skb);
> -	__be16 vlan_proto = veth->h_vlan_proto;
> -	u16 vlanid;
> -
> -	if ((vlan_proto == htons(ETH_P_8021Q) &&
> -	     dev->features & NETIF_F_HW_VLAN_CTAG_RX) ||
> -	    (vlan_proto == htons(ETH_P_8021AD) &&
> -	     dev->features & NETIF_F_HW_VLAN_STAG_RX)) {
> -		/* pop the vlan tag */
> -		vlanid = ntohs(veth->h_vlan_TCI);
> -		memmove(skb->data + VLAN_HLEN, veth, ETH_ALEN * 2);
> -		skb_pull(skb, VLAN_HLEN);
> -		__vlan_hwaccel_put_tag(skb, vlan_proto, vlanid);
> -	}
> -}
> -
>  /**
>   * stmmac_rx_refill - refill used skb preallocated buffers
>   * @priv: driver private structure
> @@ -5407,9 +5389,7 @@ static void stmmac_dispatch_skb_zc(struct stmmac_priv *priv, u32 queue,
>  	if (priv->hw->hw_vlan_en)
>  		/* MAC level stripping. */
>  		stmmac_rx_hw_vlan(priv, priv->hw, p, skb);
> -	else
> -		/* Driver level stripping. */
> -		stmmac_rx_vlan(priv->dev, skb);
> +
>  	skb->protocol = eth_type_trans(skb, priv->dev);
> 
>  	if (unlikely(!coe) || !stmmac_has_ip_ethertype(skb))
> @@ -5901,9 +5881,6 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
>  		if (priv->hw->hw_vlan_en)
>  			/* MAC level stripping. */
>  			stmmac_rx_hw_vlan(priv, priv->hw, p, skb);
> -		else
> -			/* Driver level stripping. */
> -			stmmac_rx_vlan(priv->dev, skb);
> 
>  		skb->protocol = eth_type_trans(skb, priv->dev);
> 
> @@ -7964,9 +7941,8 @@ static int __stmmac_dvr_probe(struct device *device,
>  	ndev->features |= ndev->hw_features | NETIF_F_HIGHDMA;
>  	ndev->watchdog_timeo = msecs_to_jiffies(watchdog);
>  #ifdef STMMAC_VLAN_TAG_USED
> -	/* Both mac100 and gmac support receive VLAN tag detection */
> -	ndev->features |= NETIF_F_HW_VLAN_CTAG_RX | NETIF_F_HW_VLAN_STAG_RX;
>  	if (dwmac_is_xmac(priv->plat->core_type)) {
> +		ndev->features |= NETIF_F_HW_VLAN_CTAG_RX;
>  		ndev->hw_features |= NETIF_F_HW_VLAN_CTAG_RX;
>  		priv->hw->hw_vlan_en = true;
>  	}